Machine for injection molding of the interlocking elements of slide fasteners



Maly 1,2. '1942.'

G. DAHLIN 2,282,308 MACHINE FOR INJECTION MOLDING' OF THE INTERLOCKINGELEMENTS OF SLIDE FASTENERS Filed May 4, 1959 3 Sheets-'Sheet l YInventor l Qastaf Da lin f7 f ttorngy May 12, 1942. G AHUN 2,282,308

MACHINE FOR INJECTIO MOLDING OF THE INTERLOCKING ELEMENTS OF SLIDEFASTENERS Filed May '4, 1939 3 Sheets-Shea*I 2 NNW 9310@ n NNE.) www2;

nuent or ttorney May 12, 1942.- G. DAHLIN 2,282,308

MACHINE FOR INJECTION MOLDING OF THE INTERLOCKING- ELEMENTS OF SLIDEFASTENERS Filed May 4, 1939 3 Sheets-Sheet l5' G5 Q a; h h 'QN -N I .12.fmY

"'7// 'wi N W --qL Inventor ('Iustaf Dah/in BJ @20' fdzw Attrny PatentedMay 12, 194? MACHINE FOR INJECTION MOLDING F THE INTEBLOCKING ELEMENTSFASTENEBS 0F SLIDE Guntar mmm, si. esamina, "ontario, c

assigner to Lightning Fastener-mm', um-

ited, St. Catharines, )nta'r'iqanada `vimplication'May 4, 19:9',vsexismo; eusse-. 9 Claim. (ci. isjzt'i The invention relates toimprovements in machines for injection molding of the interlockingelements of slide fasteners, of the type comprising a pair of' stringerseach consisting of a flexible supporting member or tape having aplurality of spaced interlocking members secured thereto and adapted tointerlock with the members of the other Stringer by the movement of aslider therealong.

I am aware of prior devices having the same object in view, typical ofwhich 'is that dis? from the nozzle, in which case, even if nosprue isformed, a roughness is produced on the element whichl interferes withits-operation, and it is next to impossible to prevent freezing of themolding material in the nozzle between injection periods. Anotherobjection to prior devices for such purpose arises-from the fact thatany injection molding operation requires a definite time cycle thelength of which is governed by the viscosityA of the molding material,the rate of heat dissipation from the die, and the molding pressurewhich may be employed. When one interlocking element has been molded ata time the rate of Aproduction of finished fastener Stringer, due to thelong molding cycle required for each element, has been so low as to beimpractical from an economic standpoint, and when the interlockingelements have been molded in groups. there has remained the unavoidableoperation of removing the sprue connecting the elements of each group aswell as the difliculty of maintaining the required exactly uniformspacing between individual pairs of elements at the points where thevgroups of elements join on the Stringer.

A particular object ofthe present invention is to provide amachine formolding interlocking elements directly onto the supporting memberwhereby no additional processing is required between supplying Ithemolding material to the machine and removing the finished fastenerStringer therefrom, which has a high output of finished fastenerstringer and,at the same time,

enables a relatively long molding cycle to be employed for eachindividual interlocking member,

in distinction to prior devices of the same type in which thel rate ofproduction of finished stringer is governed by thelength of the mold`ing cycle required for each interlocking member. A V

A further object is to devise a machine of the type described in whichno sprue is formed4 on the molded members. thereby eliminating waste ofmolding material and extra operations involved in removing the sprues.

' A stillfurther object is to produce a machine in which interlockingelements having depressions or undercut areas thereon, whichinterlocking members have been demonstratedy to be the strongest andmost satisfactory type, may be molded and may be ejected from themolding cavities freely and perfectly.

An additional object is to provide a machine for continuously moldinginterlocking elements on a tape which may be set up to produce asuccession of stringers of uniform length with the customary gap spacingtherebetween by a very simple adjustmentwithis absolutely positive inits action and by means of which any de- -sired length of' Stringerwithin the lengths normally used commercially may be produced on onemachine.

With the above and other objectsf'in view, which will hereinafter becomeapparent as the specification proceeds, my invention consists, in apreferred embodiment, of the construction and arrangement all ashereinafter more particularly described and illustrated with4 referenceto the accomapnying drawings in which:

Fig. 1 is a plan view of my improved machine partially broken away toreveal the interior construction; y

Fig. 2 is a side elevational view thereof Shown partially inlongitudinal vertical section;

Fig. 3 is an enlarged fragmentary side elevational view showing the tapefeed and stringer takeoff stations; and

Fig. 4 is a still further enlarged fragmentary perspective view of thediemembers of themaspending parts in the diierent gures.

In the following disclosure, material from which the interlockingelements of the fastener are to be molded will be referred to as athermoplastic molding powder, such as cellulose acetate, but it is to beunderstood that the machine is adaptable for use with any material whichmay be injected into a mold in the liquid state and hardened therein ina relatively short time, which would include certain thermosettingplastics as well as metals of low melting point, such as the orthod diecasting alloys.

Refer ing to the drawings, the machine may comprise a pair ofsubstantially cylindrical m me bers I and 2 clamped together to form a'drum And provided with a plurality of radial slots 3. The vdrum ismountedfor rotation on a shaft 4 and may be retained in position thereonby means oi' tion toward and away from each other by fins' I which slidein the grooves 3. Each die member 9 vhas a cavity II formed in one endand a groove I2 traverses each'cavity whereby each pair of die membersmay be clamped on the enlarged edge I3 of an orthodox fastener tape I4with the edge I3 received in the groove I2. .Y

The sub-base '1 is provided with a threaded collar I5 which adjustablysupports a cam ring I8 and a complementary cam ring I1 forms part of acover I8 supported on the shaft 4 which may be secured to the shaft 4 bya set screw I8 after adjustment by a nut 28. A key 2l, and a screw 22engaging a slot 23, respectively, prevent rotation of the cam rings I1and I5 about the shaft 4. The cam rings I8 and I1 engage projections 24on the die members 9 to close the respective pairs of members anda cammember 25, mounted between the rings I8 and I1 by means of'plates tegralwith the bracket 82,l thel carriage 42 and.

sub-base 43 being slotted. as indicated by the reference characters 85and 88 respectively. to permit motion of the bracket 82. The shaft 55 is28, engages them to open each pair of die mem- Y,

bers as the drum is revolved by means of a shaft 21, driven by anysuitable means such as electric motor (not shown), and which carries aworm' 28 meshing with aV gear 28 on a shaft 38 journaled inthe sub-base1v and terminating in a spur gear 3l which meshes with a ring' gear 32on the member` I. v

The tape I4 is fed between the pairs of open die members 8, 8 through anorthodox guide con-V sisting of a plate 33 mounted o'n the cam ring I8anda cover plate 34 adjustably tensioned by a knurled screw 35.

Y A depression 38 in each interlocking member 31 of the fastenerstringer is formed by a core member 38 carried on a preferably resilientplate 39, each of which may be mounted in a radial slot in the member l.When each pair of die members 9, 8 is closed, the free extremity of eachplate 39 is received in recesses 48 formed one in each of 'Y the diemembers in such manner that the molding cavity for an interlockingmember is bounded l by a pair of die members 8, 9, -a core 38, and aportion of the surface of the plate 39.

Molding material for the interlocking members is supplied to the diecavities from an orthodox pressure cylinder 4I. Such cylinder is mountedon a carriage 42 which is slidable on a sub-base 43 mountedl on the mainbase 44, which also car- A vries the sub-base 1, ways 88 travelling ingrooves 8I maintaining the cylinder in ylongitudinal alignment onthe-base 44. The cylinder 4I is provided with the usual piston 45 andreceives f `plastic material 48 from a hopper 41 to be melted by aconventional electric element 48' and forced through a conventionaltorpedo 48 to the injection nozzle 58. The piston 45 may be reciprocatedforvthe injection stroke by'a cam 5I on a shaft 52 which is journalledin a bracket 82 slidably mounted on guides 83, 83 which are supported-onthe carriage 42. Thel shaft 52 terminates in a gear 53 which meshes witha worm 54 on a shaft 55 which is journalled in a yoke 841mslidablyreceived in a sleeve 58 on the shaft 21,

through the carriage 42 and terminating in an actuating handle 59 servesto shift the carriage 42 andlock it in any desired position. Spring 89,89 on the guides 83, 83 areadapted to be compressed between' arms 88, 98on the bracket ,l i 82 and supports 8l, 9| on the carriage 42 when thecarriage is moved towards the injection end of the machine, whereby thenozzle 58 may be resiliently held against the die members 8.

The uid molding material 48 passes into the torpedo 49 through a checkvalve- 88 and the torpedo cylinder is open to an auxiliary cylinder 8lwhich acts as a surge chamber or means for maintaining a uniformhydrostatic pressure on the material in the torpedo during the return Ystroke of the piston 45. Such effect is obtained by means of a piston 82in the cylinder 8l which is permanently urged inward by a spring 83compressed between the end of the piston and a cap 84 threaded on theexterior of the cylinder 8|.

A blow hole 85 may be provided in the wall of the cylinder v8I justinside the outer limit of Ytravel of the piston 82 and through whichexcess molding material may be released in the' event that' the feedfrom the hopper 41 is in excess of the molding capacity of the machine.Additional heating elements 88 and 81 serve to maintain the moldingmaterial in a liquid state while passing to the molding cavities.

The nozzle su is or unique form and 1s provided f with a plane curvedsurface 88 which extends lfrom the nozzle along the surfaces of the diemembers 8 adjacent the nozzle proper in the direction of rotation of thedrum as indicated by 'the arrow in. Fig. 1. Such surface 88, throughwhich the transversely elongated moldingmaterial passage 88 extends,covers the portion of one die cavity II of each pair which corresponds'to part of the rear surface of a finished interlocking member 31 behindthe edge I3 of the tape, and a second plane curved surface 18 on abearing member 1I rigidly carried on a cover ring 12 and adjustable by anut 13, is coextensive with the length of the surface 88 of the nozzle58 and covers the portion of the other cavity II of each pair whichcorresponds to the remainder' of the rear surface of the interlockingmember. A second cover ring 14 similarly adjustable by a nut 15completes an enclosure for the die members 8 and their working ypartsand the two rings 12 and 14 also serve as guides around the drum for thetape I4. It will be obvious that the nozzle 58 is bevelled, as shown at18, Fig. 2, to provide clearance between itself and the member 1I forthe tape I4, and that the outer surfaces of the die members 9 are curvedplanes so that a substantially fluid-tight connection obtains betweensuch surfaces and the surfaces 88 and 18.

The operation of the machine is as follows: The shaft 21 is driven bywhatever means may be provided, which causes the drum formed by themembers I and 2 to revolve in the direction shown by the arrow in Fig. 1and as eachl pair aaaasos of die members 9, 9 approaches the injectionnozzle 59 the contours of the cam rings I6 and I'I are such that the diemembers are closed. They remain closed as they vpass the, nozzle anduntil they approach the point at which they were originally closed,whereupon they are engaged -by the surfaces of the cam member 25 to openthem. A tape I4 is fed through the guide plates 33 and 3l until it isclamped by a pair of dies which are just on the point of closing,whereupon successive die pairs clamp the tape and feed it around thedrum circumference. Thus the tape passes the nozzle 59 with its edgesclamped between successive pairs of die members 9, 9 over equidistantlyspaced portions, successive pairs of die cavities Il being brought intoyregister with the orifice 69 of the nozzle, the plane surfaces 68 and ofthe nozzle 59 and the member 1l respectively serving to complete themolding cavities for finished fastener members and the nozzle being heldagainst the die members against the reaction of the springs 89. As thecavities pass the nozzle 50 a constant head of molding material ismaintained in the nozzle by the reciprocating piston 45, the chamber 6|serving to prevent any release of pressure on the return stroke of thepiston 45, 'and'with the nozzle brought into liquid-tight frictionalengagement with the surfaces of the die members 9 by actuation of thehandle 59, each die cavity is filled with liquid molding material as itregisters with the orifice 69 and the surfaces 68 and 10 hold themolding material in the cavities at the injection pressure until solid,the solidication, of course, taking place before each individual pair ofdie members is beyond the support of the surfaces 68 andA 10. It shouldbe noted that the orifice 69 is long enough to simultaneously registerwith more than one die cavity whereby any shrinking of the contents ofany one cavity as the material strikes the cold cavity walls is made upfrom the continued pressure of liquid material from the nozzle, and alsothat the material in each cavity is "wiped off-the nozzle as the cavitypasses the nozzle so that no sprue is left on the interlocking member.By the time each pair of die members has left the surfaces 68 and 'l0the plastic material therein will be solidified suinciently to maintainits shape when supported by 'the die members alone, and as the membersdo not open until the drum has revolved approximately an additional 180the moldings will be completely solid by the time the ejection point isreached. It should be noted that as the filled cavities reach the cammember 25 which opens them, the die members 9 are withdrawn from theinterlocking members while the core members 38 remain stationary, and asthe die members are then free of the kmolded member, the finishedStringer may be rolled off the core members .by flexing the tape I4 insubstantially the same manner as one stringer is freed from its mate inoperating a, finished fastener.

As so far described, Athe machine would make continuous lengthsof'fastener stringers with the interlocking elements uniformly spaced.In order to make the relatively short lengths having a length of tape ateach end free of interlocking members required for commerce it may bedesirable to cut up such a continuous stringer into uniform lengths andstrip oil` a uniform number of interlocking elements from each end. Ifdesired, however, my machine may be made to interrupt the continuousmolding of interlocking members over predetermined lengths of the tapeat predetermined intervalsby substituting at appropriate locations onthe drum member blank die members 9, which are the same shape as thoseshown in Fig. 4, ecept that they carry no die y l cavities Il but onlythe grooves I2 for the tape margin. Thenfas the dummy die memberssurrounding the tape pass the nozzle i0, no plastic material can beinjected from the nozzle, and the tape will be provided with uniformgroups of interlocking elements spaced by blank areas. The chamber 8lwill be of particular value in such appllcation as it will accommodatethe plastic ma terial which is not injected onto the tape over the blankareas.

From the foregoing disclosure it wills obvious that I have devised amachinefor mold ig'iinter.- locking elements of a slide fastenerdirectly onto thefastener tape which is capable of a very high rate ofproduction and which, at the same time.'

permits a long molding cycle for the individual members, since eachmember is retained in its molding cavity for substantially threequarters of a revolution of the drum even. though some hundreds ofmembers may be produced by'each revolution of the drum. It will also beevident that since no sprues are produced onthe interlocking members,waste in manufacture is kept at a minimum and a smoother surface isimparted to the members. The machine is also extremely flexibleinoperation, in that stringers of different lengths may be readily made,and the control of Stringer length and spacing of theinterlockingmembers is absolutely positive and incapable of changeduring any particular setting of the control. v

While I haveshown and described in lthis application one embodimentwhich my invention may assume in practice, it will be understood thatsuch disclosure is merely for purposes of illustration and descriptionand that various other forms may be devised within the scope of myinvention as defined in the appended claims.

What I claim as my invention is:

1. In a machine for injection molding of in-` terlocking elements forslide fasteners directly onto a flexible supporting member, a train o1'pairs of die members reciprocable toward and away from each other, cammeans for successively clamping each pair of die members onto the exiblesupporting member to form a mold cavity for an interlocking member andfor maintaining a substantial proportion of consecutive pairs ofthetrain in closedposition, a molding station, means for continuouslyfeeding the train of pairs of die members with the fiexiblesupportingmember clamped therebetween past the molding station, and means at themolding station for supplying molding material to each mold cavity insuccession. A

2. In a machine for injection molding of interlocking elements forslidefasteners directly onto a flexible supporting member, a train of pairsof die members reciprocable toward and ber clamped therebetween past themolding station, and means at the molding station for sup plying moldingmaterial to each mold cavity in succession.

3. In a machine for injection molding of interlocking elements for slidefastenersdirectly onto a flexible supporting member, a rotatable drum,rotating means therefor, a stationary cam surface extending around thedrum periphery, a plurality of pairs of die members slidably mountedonthe drum periphery with one member ofeach pair in engagement with thecam surface for reciprocation towardand away from the -ether memberof/the pair'in a direction parallel-'to the drum axis on rotation of thedrum, said cam suri face being so contoured as to maintain each pairpart ofva' revolution of the drum and separated -over the lesser 'partof a revolution, means for feeding the flexible supporting memberbetween the pairs of die members when separated to be clampedtherebetween on rotation of the drum,

and stationary means for supplying molding material to the pairs of diemembers clamped ony the flexible supporting member as each of suchlpairs in succession passes therebyfv 4. In a machine for injectionmolding of initerlocking elements 'for slide` fasteners directly onto aflexible supporting member.. a rotatablei drum, rotating means therefor,a stationary cam surface extending around the drm periphery, a pluralityof pairs of die members slidably mounted on the drum periphery with 'onemember of each pair in engagement with the cam surface for reciprocationtoward and'v away. from the other member of the pair in a directionparallel to the drum axis on rotation of the drum, said cam'surfacebeing so contouredv as to maintain each pair of die members injuxtaposition over the greater vpari; of a revolution of the drum andposition'and registering with the mold cavity formed thereby, and meansfor maintaining pressure on the contents of the supply chamber.

8. A machine for injection molding of interlocking elements for slidefasteners directly onto' a tape comprising a base, a drum .journalledtherein and provided with a plurality of radial slots equidistantlyspaced around its periphery, a pair of die members slldably disposed ineach slot. a pair of cam surfaces rigid1y, mounted'on the base andextending around the greater portion of the drum periphery for closingthe pairs of die members and maintaining them closed over of die membersin juxtaposition over the greater members when in the open position tobe clamped the greater part' of a revolution of the drum, a

- second pair of cam surfaces rigidly mounted on the base adapted toengage the pairs of die mem bers over the lesser portion of the drumperiphery for opening -the members, means for continuously rotating thedrum, means for feeding a tape continuously between the pairs of die"therebetween inthe closed position, a molding material supply chambermounted on the base andI means for conducting molding material underpressure from the supply'chamber to each pairl of closed die members asthe closed members pass the chamber.

7. In a machinev as claimed in claim 6, a core member'radially disposedon the drum periphery separated over the lesser part of a revolution, a

core member and a resilient support therefor disposed between each pairof the pairs of die members and each cooperating with one pair of diemembers when such members Lare juxtaposed to' form a mold cavity'for aninterlocking member,

' means for feeding the exiblesupporting member between successive.pairs of die members when separated to be clamped therebetween onrotation of the drum, and stationary means for supplying moldingAmaterial to each mold cavity as each cavity in succession passesthereby.

.- 5.' A machine as claimed in claim 4, wherein s. 'A machine es claimedm claim e wherein `the means for conducting molding material underpressure comprises a conduit from the supply chamber,- means formaintaining the conduit outlet in frictional substantially fluid-tightengagement with the surfaces of the die members as the members pass theoutlet duringqotation of the drum, and means for maintaining a constanthydrostatic pressure on molding material in the conduit, theinterlocking element molding cavity .'iormed by each pair of closed diemembers being adapted to register with thev conduit outlet as themembers pass the conduit on rotation of the drum.

9. A machine as claimed in claim 6 wherein a 'group of consecutive pairsof said die members are replaced by a group of ypairs of blank tape themeans for applying molding material to the mold cavity comprise amolding material supply chamber, a conduit leading therefrom andterminating against the die members in the juxtaposed `c-lamping memberswhich block said means for conducting molding material as the tapeclamping membrs pass said chamber.v

GUSTAF DAHLIN.

